Vermiculite ore mined in Libby, Montana, contained an asbestiform mineral best described as a tremolite-actinolite-[unreadable] richterite-winchite transition fiber. A recent study of 7,307 miners, millers, and community[unreadable] residents in Libby showed increased prevalence of radiographic abnormalities consistent with previous[unreadable] exposure to asbestos. The vermiculite ore was shipped to many 'expansion plants' throughout the United[unreadable] States, including one in Marysville, Ohio. Ore from Libby was used in Marysville from 1957 to 1980. In[unreadable] 1980 a cross-sectional study of 513 workers from the Marysville plant demonstrated that cumulative fiber[unreadable] exposure was correlated with pleural changes on chest radiographs. A follow-up study of a large subset of[unreadable] these same workers was completed in 2003. With the additional 23 years of latency, there was an[unreadable] increased prevalence, and a significant trend of increased prevalence of radiographic changes, mostly[unreadable] pleural, in relation to cumulative fiber exposure. Previous studies have shown that household contacts of[unreadable] asbestos-exposed workers may be at increased risk of asbestos-related disease. The objectives of the[unreadable] present study are to: 1) determine the prevalence of radiographic changes among household contacts of the[unreadable] Marysville, Ohio, vermiculite workers; and, 2) determine if household contacts with increasing exposure[unreadable] demonstrate an increasing prevalence of radiographic changes. Posteroanterior radiographs will be[unreadable] obtained from household contacts of index workers. B readings from these radiographs will be interpreted[unreadable] using the International Classification of Radiographs of Pneumoconiosis (2000). Radiographic outcomes for[unreadable] analyses will include costophrenic angle blunting only, pleural plaques with or without calcification, diffuse[unreadable] pleural thickening with or without calcification, interstitial changes, and combined pleural/interstitial changes.[unreadable] Analyses will be adjusted for potential confounders such as age, gender, cigarette smoking, body mass[unreadable] index, and other environmental and occupational exposures. In addition, tests for trend will be conducted to[unreadable] determine significant increasing pleural changes in household contacts by increasing indices of exposure.